A FACILE SYNTHESIS OF BIS(ETHYLENEDITHIO)TETRATHIAFULVALENE

5,6-Dihydro-1,3-dithiolo[4,5-b][1,4]dithiin-2-one (3) was prepared in one step starting from thiapendione (1; [1,3]dithiolo[4,5-d][1,3]dithi ole-2,5-dione) in 55 % yield via 4,5-dimercapto-1,3-dithiol-2-one (2). Coupling of 3 in triethyl phosphite gave bis(ethylenedi-thio)tetrathi afulvalene [4; BEDT-TTF; -dihydro-1,3-di-thiolo[4,5-b][1,4]dithiinylid ene)] in 85 % yield. The conditions for the formation of intermediates like 2 by basic cleavage of 1 are briefly discussed.